title: First-principles study of hydrogen vacancies in sodium alanate with Ti substitution.
abstract: In order to clarify the effect of hydrogen vacancies on the stability and structure of sodium alanate, NaAlH(4), with and without Ti substitution for Al, first-principles electronic structure calculations were carried out. The relative thermodynamic stability of the Ti dopant and the H vacancy in a supercell was obtained. For the Ti-doped Na(16)Al(16)H(64) supercell calculations, it was preferable to perform the initial substitution with a cluster of TiAlH(n). We showed that substitution of a Ti atom for an Al atom in Na(16)Al(15)TiH(63) with H vacancies increases the stability of the structure. A density of states analysis revealed weakening of the bond strength corresponding to increase in the bond length.
authors.affiliation: Research Institute for Computational Sciences (RICS), National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568, Japan. kou.ou@imr.tohoku.ac.jp
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Akinori
authors.initials: A
authors.lastname: Tezuka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ogawa
authors.forename: Tamio
authors.initials: T
authors.lastname: Ikeshoji
mesh_terms: D000042:Absorption; D000535:Aluminum / Q000737:chemistry*; D017607:Aluminum Compounds / Q000737:chemistry*; D001703:Biophysics / Q000379:methods; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D015394:Molecular Structure; D010825:Physics / Q000379:methods; D017670:Sodium Compounds / Q000737:chemistry*; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D017670:Sodium Compounds; C513667:sodium aluminum hydride; D006859:Hydrogen; D000535:Aluminum; D014025:Titanium